diff --git a/README.md b/README.md
index baae34f8..f12ddfa2 100644
--- a/README.md
+++ b/README.md
@@ -288,6 +288,7 @@ Built-ins:
 | `gemini`   | native (`gemini --acp`)                                                | [Gemini CLI](https://github.com/google/gemini-cli)                                                              |
 | `cursor`   | native (`cursor-agent acp`)                                            | [Cursor CLI](https://cursor.com/docs/cli/acp)                                                                   |
 | `copilot`  | native (`copilot --acp --stdio`)                                       | [GitHub Copilot CLI](https://docs.github.com/copilot/how-tos/copilot-chat/use-copilot-chat-in-the-command-line) |
+| `droid`    | native (`droid exec --output-format acp`)                              | [Factory Droid](https://www.factory.ai)                                                                         |
 | `kimi`     | native (`kimi acp`)                                                    | [Kimi CLI](https://github.com/MoonshotAI/kimi-cli)                                                              |
 | `opencode` | `npx -y opencode-ai acp`                                               | [OpenCode](https://opencode.ai)                                                                                 |
 | `kiro`     | native (`kiro-cli acp`)                                                | [Kiro CLI](https://kiro.dev)                                                                                    |
diff --git a/agents/Droid.md b/agents/Droid.md
new file mode 100644
index 00000000..644f19fe
--- /dev/null
+++ b/agents/Droid.md
@@ -0,0 +1,5 @@
+# Droid
+
+- Built-in name: `droid`
+- Default command: `droid exec --output-format acp`
+- Upstream: https://www.factory.ai
diff --git a/agents/README.md b/agents/README.md
index a0f18955..e6d4f1c9 100644
--- a/agents/README.md
+++ b/agents/README.md
@@ -9,6 +9,7 @@ Built-in agents:
 - `gemini -> gemini --acp`
 - `cursor -> cursor-agent acp`
 - `copilot -> copilot --acp --stdio`
+- `droid -> droid exec --output-format acp`
 - `kimi -> kimi acp`
 - `opencode -> npx -y opencode-ai acp`
 - `kiro -> kiro-cli acp`
@@ -20,6 +21,7 @@ Harness-specific docs in this directory:
 - [Gemini](Gemini.md): built-in `gemini -> gemini --acp`
 - [Cursor](Cursor.md): built-in `cursor -> cursor-agent acp`
 - [Copilot](Copilot.md): built-in `copilot -> copilot --acp --stdio`
+- [Droid](Droid.md): built-in `droid -> droid exec --output-format acp`
 - [Kimi](Kimi.md): built-in `kimi -> kimi acp`
 - [OpenCode](OpenCode.md): built-in `opencode -> npx -y opencode-ai acp`
 - [Kiro](Kiro.md): built-in `kiro -> kiro-cli acp`
diff --git a/skills/acpx/SKILL.md b/skills/acpx/SKILL.md
index 5fc0a36c..99a30ca5 100644
--- a/skills/acpx/SKILL.md
+++ b/skills/acpx/SKILL.md
@@ -71,15 +71,17 @@ If prompt text is omitted and stdin is piped, `acpx` reads prompt text from stdi
 
 Friendly agent names resolve to commands:
 
+- `pi` -> `npx pi-acp`
+- `openclaw` -> `openclaw acp`
 - `codex` -> `npx @zed-industries/codex-acp`
 - `claude` -> `npx -y @zed-industries/claude-agent-acp`
-- `copilot` -> `copilot --acp --stdio`
 - `gemini` -> `gemini --acp`
-- `openclaw` -> `openclaw acp`
+- `cursor` -> `cursor-agent acp`
+- `copilot` -> `copilot --acp --stdio`
+- `droid` -> `droid exec --output-format acp`
 - `kimi` -> `kimi acp`
 - `opencode` -> `npx -y opencode-ai acp`
 - `kiro` -> `kiro-cli acp`
-- `pi` -> `npx pi-acp`
 - `kilocode` -> `npx -y @kilocode/cli acp`
 - `qwen` -> `qwen --acp`
 
diff --git a/src/agent-registry.ts b/src/agent-registry.ts
index 4fbd6259..6dd9b990 100644
--- a/src/agent-registry.ts
+++ b/src/agent-registry.ts
@@ -12,6 +12,7 @@ export const AGENT_REGISTRY: Record<string, string> = {
   gemini: "gemini --acp",
   cursor: "cursor-agent acp",
   copilot: "copilot --acp --stdio",
+  droid: "droid exec --output-format acp",
   kimi: "kimi acp",
   opencode: "npx -y opencode-ai acp",
   kiro: "kiro-cli acp",
diff --git a/test/agent-registry.test.ts b/test/agent-registry.test.ts
index 4a30dc79..f5b16d41 100644
--- a/test/agent-registry.test.ts
+++ b/test/agent-registry.test.ts
@@ -20,7 +20,7 @@ test("resolveAgentCommand returns raw value for unknown agents", () => {
 test("listBuiltInAgents preserves the required built-in example order", () => {
   const agents = listBuiltInAgents();
   assert.deepEqual(agents, Object.keys(AGENT_REGISTRY));
-  assert.deepEqual(agents.slice(0, 7), [
+  assert.deepEqual(agents, [
     "pi",
     "openclaw",
     "codex",
@@ -28,6 +28,12 @@ test("listBuiltInAgents preserves the required built-in example order", () => {
     "gemini",
     "cursor",
     "copilot",
+    "droid",
+    "kimi",
+    "opencode",
+    "kiro",
+    "kilocode",
+    "qwen",
   ]);
 });
 
diff --git a/test/integration.test.ts b/test/integration.test.ts
index 31b89e61..3e18083d 100644
--- a/test/integration.test.ts
+++ b/test/integration.test.ts
@@ -72,6 +72,33 @@ test("integration: built-in cursor agent resolves to cursor-agent acp", async ()
   });
 });
 
+test("integration: built-in droid agent resolves to droid exec --output-format acp", async () => {
+  await withTempHome(async (homeDir) => {
+    const cwd = await fs.mkdtemp(path.join(os.tmpdir(), "acpx-integration-cwd-"));
+    const fakeBinDir = await fs.mkdtemp(path.join(os.tmpdir(), "acpx-fake-droid-"));
+
+    try {
+      await writeFakeDroidAgent(fakeBinDir);
+
+      const result = await runCli(
+        ["--approve-all", "--cwd", cwd, "--format", "quiet", "droid", "exec", "echo hello"],
+        homeDir,
+        {
+          env: {
+            PATH: `${fakeBinDir}${path.delimiter}${process.env.PATH ?? ""}`,
+          },
+        },
+      );
+
+      assert.equal(result.code, 0, result.stderr);
+      assert.match(result.stdout, /hello/);
+    } finally {
+      await fs.rm(fakeBinDir, { recursive: true, force: true });
+      await fs.rm(cwd, { recursive: true, force: true });
+    }
+  });
+});
+
 test("integration: exec forwards model, allowed-tools, and max-turns in session/new _meta", async () => {
   await withTempHome(async (homeDir) => {
     const cwd = await fs.mkdtemp(path.join(os.tmpdir(), "acpx-integration-cwd-"));
@@ -1529,6 +1556,44 @@ async function writeFakeCursorAgent(binDir: string): Promise<void> {
   );
 }
 
+async function writeFakeDroidAgent(binDir: string): Promise<void> {
+  if (process.platform === "win32") {
+    await fs.writeFile(
+      path.join(binDir, "droid.cmd"),
+      [
+        "@echo off",
+        "setlocal",
+        'if /I "%~1"=="exec" shift',
+        'if /I "%~1"=="--output-format" shift',
+        'if /I "%~1"=="acp" shift',
+        `"${process.execPath}" "${MOCK_AGENT_PATH}" %*`,
+        "",
+      ].join("\r\n"),
+      { encoding: "utf8" },
+    );
+    return;
+  }
+
+  await fs.writeFile(
+    path.join(binDir, "droid"),
+    [
+      "#!/bin/sh",
+      'if [ "$1" = "exec" ]; then',
+      "  shift",
+      "fi",
+      'if [ "$1" = "--output-format" ]; then',
+      "  shift",
+      "fi",
+      'if [ "$1" = "acp" ]; then',
+      "  shift",
+      "fi",
+      `exec "${process.execPath}" "${MOCK_AGENT_PATH}" "$@"`,
+      "",
+    ].join("\n"),
+    { encoding: "utf8", mode: 0o755 },
+  );
+}
+
 async function withTempHome(run: (homeDir: string) => Promise<void>): Promise<void> {
   const tempHome = await fs.mkdtemp(path.join(os.tmpdir(), "acpx-integration-home-"));
   try {